A Dram of Poison — Charlotte Armstrong

A longtime bachelor finally loves -- only to suffer corrosive jealousy

For five decades, Kenneth Gibson lives quietly, now teaching poetry to undergrads. His life is comfortable and dull, until he meets and marries helpless Rosemary 32. Cared for, her depression fades, his wan wife gains bouncy beauty and vigorous health. He falls in love. But does she?

After a car accident, his pushy practical spinster sister moves in to assist, and stays, warm California to her liking. Ethel compels both to see how their winter-summer romance is an impossible dream. Landlord Paul is younger, handsome and wealthy, a better match for his "mouse".

Gibson sadly puts tasteless odorless instant poison in an innocuous olive oil bottle. In his cloudy confusion, he forgets the fatal dose on a bus. Who will die and when?